In the production of glass containers, particularly those which are of relatively short height and have threaded necks, for example, those glass containers used to package nail polish, they have sometimes been produced with minute cracks at the base of the neck or finish. These small cracks, or checks, as they are termed, may lead to a failure of the neck of the container when the container is filled with product and the threaded closure applied. Failure may also occur in containers with these small checks formed therein, when the closure is being removed by the consumer, or when re-applying the closure after having used a portion of the product.
There have been standard impact testing equipment for selecting glass containers; however, these have been of a type where a pendulum is used to swing an indentor into a container and typically these tests involve taking a sample container and impacting the container at increasing pendulum heights until such time as the container will fail. Further tests have been made on containers, again using the pendulum, where a percentage of the containers are impacted to a given degree as a representative sample of the containers and it is determined from this what the percentage of failure of the entire production run might be.
With this in mind, it is an object of this invention to provide an apparatus which may be located in the glass manufacturing plant and which will separate those containers which have defective or checked finishes, from those which are of acceptable strength. It is also an object of this invention to provide a method of testing the strength of the necks of glass containers by impacting the necks of the containers from the side at a plurality of points about the circumference of the neck of the container; such impacting resulting in failure of the necks which are defective; and the passing of those which are acceptable.
The present invention has as a further objective the testing of all bottle finishes of a production run immediately after they have been completely formed and have passed out of the annealing lehr.